Field of the Invention
The disclosure relates to a process controller and an updating method thereof.
Priority is claimed on Japanese Patent Application No. 2014-008047, filed Jan. 20, 2014, the contents of which are incorporated herein by reference.
Description of Related Art
A process control system controlling various types of state quantity (for example, pressure, temperature, and flow quantity of fluid) is installed in a plant and a factory (hereinafter called simply “plant” as a generic name of them). Specifically, Japanese Patent No. 4399773 discloses that a controller (process controller) which is a core of the process control system collects detection results of sensors (for example, a flowmeter and a thermometer), the controller calculates a manipulation value of an actuator (for example, a valve) in accordance with the detection results, and the controller manipulates the actuator in accordance with the calculated manipulation value. By these processes, the various types of the state quantity described above are controlled.
Although the process control system is established by using a dedicated device for exclusive use, a recent process control system is being opened and often established by using a general-use device (a computer or a workstation) of which specifications are opened. In the process control system using the general-use device, same as a general information system, there is a need to switch over (update) a platform includes hardware, an operating system (OS), and so on. The platform is switched over so as to, for example, expand a function of the platform or correct a failure and weakness of the platform.
Although the process control system is often established singly, the recent process control system is often connected to another information system performing a production management or the like so as to improve productivity of the plant. In a case that the process control system is connected to another information system, there is a risk of external cyber-attacks. For the reason, it is important to switch over the platform continuously.
The process controller switches over the platform so as to shorten the downtime of a control performed by the control application as much as possible. Specifically, the platform of the process controller is switched over by the following procedures 1 to 4. “Old process controller” means a process controller used before the platform is switched over. “New process controller” means a process controller to be used after the platform is switched over.
1. Starting the new process controller so as to make the control application be settable.
2. Transferring a setting of the control application which had run in the old process controller to the new process controller.
3. Causing the old process controller to stop. (By this task, the network is disconnected, and the control application comes to a stop.)
4. Booting a control application in the new process controller.
In the procedures described above, the old process controller is caused to stop (procedure 3) before booting the control application in the new process controller (procedure 4). By these procedures, a competition of a plurality of same control applications is preventable. However, in a case of switching over the platform by the procedures 1 to 4, the control application is caused to stop running when the old process controller is caused to stop, the operation states of the old process controller (an operation state of the control application, an operation state of the operating system, a communication state, and so on) is not taken over by the new process controller.
In a case that the control application is booted in the new process controller without taking over the operation state, the control application must start an initializing task. For the reason, there is a possibility that the control operation is to be discontinuous. “The control operation is to be discontinuous” means, for example, that an operation to be performed intrinsically is not performed or that same operations are performed redundantly. In a case that the control operation is discontinuous, work-in-process is seriously damaged in accordance with characteristics thereof, and also there is a possibility that a facility which is a control object is damaged.